Power-driven tail-gate elevator



July 13, 1954 Q. D. coRLEY, JR 2,683,539

POWER-DRIVEN TAIL GATE ELEVATOR Filed Aug. 23, 1951 5 Shets-Sheei'. l

ATTORNEY Q. D. CORLEY, JR 2,683,539

POWER-DRIVEN TAIL GATE ELEVATOR yJuly 13, 1954 Filed Aug. 23, 1951 5 Sheets-Sheet 2 INVENTOR www ATTORNEY July 13, 1954 Q. D. coRLEY, JR

POWER-DRIVEN TAIL GATE ELEvAToR 5 Sheets-Sheet 5 Filed Aug. 23, 1951 flllllI llll,

lNvENToR ATTORNEY July 13, 1954 Q. D. coRLEY, JR

POWER-DRIVEN TAIL GATE ELEVATOR 5 sheets-sheet 4 Filed Aug. 25, 1951 INVENTR gzln C21/legi ATTORNEY July 13, 1954 Q. D. coRLEY, .1R

POWER-DRIVEN TAIL GATE ELEVATOR 5 Sheets-Sheet 5 Filed Aug. 23, 1951 UM I wu.. H\ MIM u. M ,M 5 www; QM/w W Z -l ||V. m w W\\ INVENTOR Qzzwzlfz (br/@jr BY Qatw..

ATTORNEY Patented July 13, 1954 POWER-DRIVEN TAIL-GATE ELEvAToa Quentin D. Corley, Jr., Balles, Tex., assignor, by mesne assignments, to L. A. Young Spring & Wire Corporation, Detroit, Mich., a corporation of Michigan Application August 23, 1951, Serial No. 243,264

9 Claims.

This invention relates to tail-gate mechanism for trucks and the like, and more particularly to a hydraulic power-operated tail-gate having an automatic drop platform-ramp forming a low loading section. The present invention is a modication of U. S. Patent #2,469,321 of May 3, 1949, wherein a similar hydraulic power-operated tail-gate structure is illustrated and described. The present invention pertains to a modified tailgate structure wherein there is provided a drop center section forming a platform-ramp for easy loading and unloading of the tail-gate.

It is an object of this invention to provide a power-operated tail-gate of the type described, with a low loading section or ramp which is attached to and forms a part of the tail-gate but is movable relative thereto so as to provide a long sloping ramp for receiving loads to be raised by the tail-gate.

Another object of this invention is to provide a power-operated tail-gate having a drop center platform-ramp which section is raised automatically upon the elevation of the power-operated tail-gate from its lowermost ground or floor horizontal position to the level of a truck floor.

Another object of the invention is to provide a unitary power-operated tail-gate and ramp section, the latter being of any suitable length and adapted to receive the load to be supported and elevated by the power-operated tail-gate and wherein upon elevation of the tail-gate carrying the platform-ramp to move the ramp in position so that its upper surface is substantially flush with the upper surface of the tail-gate.

Still another object of the invention is to pro- 5,.,

vide an improved unitary tail-gate and drop ramp section, as described, and operating mechanism therefor which forms a compact unit, and which structure is adapted to be readily installed on divers types of truck bodies and operated to .f

make it easy to load and unload the truck.

Other objects and advantages oi the invention will be apparent from the following description taken in conjunction with the drawings forming a part of this specification and in which- Fig. 1 is a rear elevational view in perspective of a transport truck equipped with a power-operated tail-gate having a drop center platformramp constructed in accordance with this invention.

Fig. 2 is a side elevational view showing the power-operated tail-gate in a lowered horizontal position on the ground or floor to receive a load to be transferred to the body of the truck, the body of the truck being shown partly broken away and the uppermost position of the tail-gate and associated drop platform-ramp being shown in dotted line.

Fig. 3 is a plan view of the power-operated tail-gate shown in Fig. l and illustrating the construction of the drop center platform-ramp section, certain parts of the tail-gate being broken away to show the construction and mechanism for automatically raising the platformramp more clearly; the broken lines on the drawings are indicative that the dimensions of the tail-gate and drop platform-ramp section are immaterial.

Fig. 4 is an enlarged detail side elevational view of the power-operated tail-gate and drop platform-ramp and illustrating the ramp in its lowered loading position with respect to the tailgate.

Fig. 5 is a similar view as in Fig. 4 and illustrating the drop platform-ramp in its raised position where its surface is substantially flush with that of the tail-gate, and which position is automatically obtained upon elevation of the tailgate from its ground or floor position to the level of the truck floor.

Fig. 6 is a diagrammatic view illustrating the leverage action and arrangement for raising and lowering the platform-ramp of the power-operated tail-gate.

Fig. '7 is a fragmentary detail perspective view on an enlarged scale and illustrating the linkage arrangement for connecting and latchng the platform-ramp in its elevated position.

Referring to the drawings, particularly Figs. 1 and 2, there is illustrated one embodiment of the invention as installed on a transport truck.

The truck comprises a body l provided with a power-operated tail-gate generally indicated at 2. The tail-gate and associated mechanism for elevating and lowering the same is secured to the chassis 3 of the truck body, being suitably mounted on the rear of the chassis by a depending bearing bracket ll. This bracket is centrally disposed and inclined downwardly and forwardly so as to provide a pair of bearing members 5 which are adapted to receive and have journaled therein for rotary movement an outer transverse shaft 6. The shaft 6 is provided with an inner transverse shaft l which is suitably journaled therein for rotation independently of the outer shaft 6. The construction and operation of the power-operated tail-gate is similar to that disclosed and described in the aforementioned patent.

The tail-gate 2 is provided with a central drop platform-ramp 8 which is operatively connected to and carried by the tail-gate so that when the tail-gate is raised from its lowered position to the fioor of the truck the platform-ramp is automatically raised to a position flush with the floor of the tail-gate. The outer shaft 5, as shown in Figs. i and 2, is provided with a pair of arms 2i) which extend upwardly and rearwardly at an inclination to the tail-gate in its lower position. The outer ends of the arms 2li are provided with a pivot pin 2i which connects with the end of the piston 22 of the cylinder 23 arranged at an inclination and extending downwardly and rearwardly from the truck body chassis, and which is connected at its upper end to the chassis by a suitable pivot 24 at a point below the upper face of the bottom of the truck body. The shaft E is also providedadjacent its outer ends with a pair of lifting arms 25 which are rigidly connected to the outer shafts i so as to be swung about upon rotation of the shaft.

Preferably the lifting arms 25 are formed of I-beams or other suitable material having the required strength for supporting the tail-gate 2 and platform-ramp 8 as a unitary structure. The lifting arms 25 are secured at their outer ends by means of plates 25 with the tail-gate, being suitably connected thereto by means of the pivot rod 25. With the introduction of fluid under pressure into the cylinder 23 to actuate the piston 22, the outer shaft B is rotated so as to swing the lifting arms 25 to raise or lower the tailgate 2. This raising and lowering of the tailgate is illustrated in Fig. 2 in the dotted line, the same being raised from a horizontal position level with the ground or floor to a horizontal position wherein the tail-gate is level with the floor of the truclr body, thus enabling the loa-:l to be lifted from the ground and readily transferred into the truck. The lifting arms swing through an arc indicated by dot-and-dash lines 21 in Fig. 2 and as illustrated in dotted lines the tail-gate is carried in a substantially horizontal position from its lowermost horizontal p1. ition to a position which is substantially flush the floor of the truck and vice versa, the tailgate as well as the drop platform-ramp 3 constituting a platform where the operator may stand while transferring the load from the ground or oor to the body of the truck or from the truck to the ground.

The pivot rod 25 preferably consists of a transverse shaft journaled in suitable supporting brackets 23 on the tail-gate, the pvot 2li constituting a pintlc on which the tail-gate swings in lowering it from a vertical closed position to the open horizontal position` as illustrated in Figs. l and 2, the latter being shown in dotted lines.

The ends 29 of the inner shaft 1 are extended somewhat beyond the outer ends of the shaft 6 and are provided with terminal oppositoly eX- tended radialiy disposed arms 3e which are connected by pivots 3l to the adjacent ends of pair of spaced parallel links 32 and which preferably consist of fiat bars connected by pivots Si@ to the hinged lower edge of the tail-gate at opposite sides of the pintle or pivot rod 253. This inner shaft 'l is adapted to be rotated so as to carry the arms B through an arc of approximately 45. This motion of the arms is transmitted by the parallel links 32 to the tail-gate 2 so as to swing the same downwardly from the vertical position as shown in Fig. l to the horizontal position illustrated in dotted line in Fig. 2, and vica versa.

Any other' suitable link connection may, of course, be provided for transmitting motion from the inner shaft to the tail-gate for bringing about the swinging of the same about its horizontal shaft 26.

The rotary movement of the inner shaft l is effected by a piston 34 operating in a cylinder 35 extending longitudinally of one of the angle bearing brackets of the chassis 3 and arranged at a slight inclination thereto and connected at its upper end by a suitable pivot 36 to the bracket 31 mounted on the chassis. The lower end of the piston S4 is connected by a pivot 33 to an angle iron 40 fixed to the adjacent outer extended end. of the inner shaft I and extending downwardly and rearwardly therefrom, as illustrated in Fig. 2.

The tail-gate 2 and the platform-ramp 8 are operable as a unit in swinging the tail-gate from a vertical to a horizontal position, and also when lowering the tail-gate from an elevated horizontal position contiguous to the floor of the body of the truck to the ground and while elevating the tail-gate to its horizontal position and also while swinging the tail-gate from its horizontal position to its vertical closed position as shown in Fig. l.

The tail-gate and platform-ramp construction, as illustrated in Figs. 2 through 5, comprises a frame structure which preferably is fabricated from steel plates 4l, the same being welded or otherwise rigidly secured together and fastened to the parallel side members 42 so as to form a reinforced sturdy support for a loadreceiving surface plate 43.

The tail-gate comprises a U-shaped structure having an elongated open section 44 for receiving the platform-ramp 8, as illustrated in Fig. 3.

The platform-ramp 8, as illustrated in Figs. 3, 4 and 5, and which may be of any desired climension depending upon the size of the tail-gate and loading requirements, comprises a substantially flat, level section 45 and an outwardly sloping integral section 46 which extends outwardly from the tail-gate. The platform-ramp 8y which is suitably formed of sheet metal and having a cleated or friction-type surface, is supported for automatic movement relative to the tail-gate in the opening 44, the same being trunnion mounted therein for swinging through an arc in the opening 44 so that the same can be raised and lowered to utilize the platform-ramp for loading and unloading of the tail-gate.

Spaced rods 48 and 49 support the platformramp 8 and are arranged to be swung through an arc in the opening 44. The outer ends of each of the rods 45 and 49 are carried by a pair of triangular-shaped bell cranks 56,50', and 5l, 5|', the rods being pivotally secured thereto, as at 52, 52 and 53, 53', respectively.

The bell cranks and 50' for swingably supporting the rod 48 are rigidly attached to a shaft 56 as at 51 and 51', the shaft extending transversely of the opening 44 and being mounted adjacent the inner closed end thereof so that when .the platform-ramp 8 is swung outwardly and downwardly, as illustrated in Fig. 3, it does not interfere with the shaft. The shaft 56 is suitably journaled at its opposite end in the frame members 58 and 58'. The bell cranks 5I and 5I are similarly rigidly secured as at 60 and 68' to the outer ends of the stub shafts 6l and 6l', respectively, the stub shafts being suitably journaled in the side plates 63 and 63 Vof the tailgate sub-structure.

Suitable mechanism is provided for automatically raising the platform-ramp 8 upon elevation of the tail-gate from its horizontal ground or floor position, as illustrated in full lines in Fig. 2, to its corresponding horizontal raised position, as shown in dotted lines in the same figure, and wherein the tail-gate is brought ush with the lioor of the truck body. The preferred embodiment for accomplishing this is illustrated in Figs. 3, 4 and 5 and comprises mounting a pair of crank arms 65 and 65 which are arranged at opposite sides of the shaft 56 and rigidly attached at one end to an extension thereof as shown at 64 and 64. Each pair of crank arms is pivotally fastened together by an apertured lug 66 and 66', respectively, the lugs being adapted to slidably receive the rods 61 and El' which are threaded on their outer end to receive a pair of lock nuts 68 and 68', respectively.

For reciprocating the rods 6'! and El the same are pivotally secured as by means of bolts 69 and 69 to lugs l0 and '10', respectively, which lugs are integral with the torque tube members 'Il and 7l', the torque tubes being rigidly connected to the elevating arms 25, whereby, upon elevation of the tail-gate from its lower-most position to the level of the fioor of the truck, as shown in Fig. 2, the torque tube portions 'Il and 'Il' on the pivot rod rotate counter-clockwise, moving the rods 6'! and S1 to the left as shown in Fig. 3.

This rotation of the torque tubes 'Il and 1I counter-clockwise rotates the shaft 56 counterclockwise through the connecting rods Si and 6l' and sets of crank arms 65 and 65', thus raising the triangular-shaped bell cranks 5E] and 50', carrying the platform-ramp supporting rods 48 and 49.

The cranks 5G and-59' are pivotally connected to the corresponding cranks 5I and 5| by means of the links 'l2 and 72', respectively, the link 'I2 being fastened at 'M to the crank 50 and at its opposite end at l5 to the crank 5|. Link 12 is similarly operatively connected to the links 5G and 5! so that the triangular-shaped bell cranks are all tilted simultaneously so as to exert an even and balanced lifting force on the platformramp to elevate the same during raising of the tail-gate from the ground position to a position flush with the floor of the truck body.

To provide means for locking the platformramp 8 in its raised position, such as illustrated in Figs. 5 and 7, a rod 8l) extending transversely of the tail-gate and adjacent the inner end, is suitably journaled in the tail-gate frame and provided on its outer ends with handles 82 and 82 -l for manipulation of the same. Fastened to the rod @El adjacent the outermost crank arms 65a and h, respectively, are latches 85 and 85. The latches are fixed to swing upon rotation of the rod SQ and comprise a notch 36 and 86' on the outer ends of the latch members 85 and 85', respectively, which are adapted to engage over the end of a cooperating abutment member 8'! and tl', the latter members being welded or otherwise securely fastened to the crank arms a and 55h, respectively. Two latches are preferably utilized, one opposite each end of the shaft 56, so as to prevent the setting up of twisting forces on the mechanism when the platform-ramp is loaded and held in its uppermost position by the latches. By varying the position of the lock nuts 68 and S8' on the rods 6'! and 61', respectively, the effective stroke of the rods can be adjusted so that the platform-ramp 8 can be brought to rest iiush with the top loading surface of the tail-gate floor portion 44 whereby loads can be readily transferred from the tail-gate to the ramp or vice versa.

In Fig. 6 there is illustrated diagrammatically the leverage action in bringing about the elevation of the platform-ramp to a position wherein the flat level surface of the platform-ramp section 45 is brought flush with the iioor portions 43 of the tail-gate.

As shown, the triangular-shaped bell crank members 5l] and 5l are linked together and support the rods 48 and 49 upon which the platform-ramp 8 is carried or adjustably tilted about their pivot points 55 and 60, respectively, these pivot points being fixed to the sub-frame of the tail-gate as shown in Figs. 4 and 5. Rotation of the torque tube sections 'il and ll', as described, brings about reciprocation of the arms 6'! and 61 and raising of the platform-ramp during elevation of the tail-gate from the ground to the floor of the truck body. When the platform-ramp has been elevated suiiiciently the latches and 85 engage over the abutment lugs 8'! and 87 and hold the platform-ramp in its raised position until it is desired to lower the same. The lost motion in the rods 6'! and 61' with respect to the apertured lugs 66 and 66', permits the tail-gate to be lowered to the ground position without dropping the platform-ramp, inasmuch as it remains in its raised position so long as the latches 85 and 85' are interlocked with the abutments 8'!, 81', respectively. Lowering of the platform-ramp is accomplished by merely operating the lever B2 or S2' so as to release the latches 85 and 85 from engagement with their respective abutment lugs.

In accordance with the invention there is thus provided an improved power-operated tail-gate which provides a platform and sloping ramp with the tail-gate as a unitary structure. A low loading, long sloping section is provided for the power-operated tail-gate which makes it very easy to load and unload the tail gate and bring the load in position to be transferred to the truck body.

The mechanism for supporting the platformramp, as described, is operatively connected to the tail-gate elevating structure whereby upon raising of the tail-gate from its lowermost horizontal position to the level of the truck body floor on which the tail-gate is installed, the platform ramp section is automatically elevated whereby the dat, level portion thereof is brought substantially flush with the floor of the tail-gate. By this improved construction of a power-cperated tail-gate no additional ramp or sloping section is required to yfacilitate the loading of the tail-gate.

While the improved tail-gate and platformramp structure of this invention has been described and illustrated as installed on a transport truck, it is to be understood that the tailgate mechanism may be utilized with advantage on various types of trucks or transport means. Further, while the preferred embodiment of the invention has been shown and described, it is to be also understood that the particular embodiment shown on the drawings and described in detail may be modified within the spirit and scope of this invention and is not to be limited except as so restricted in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A power operated tail-gate for a truck body having associated therewith a central section comprising a platform-ramp for assisting in loading and unloading operations, said platformramp constituting a central drop section having a sloping forward portion and movably carried within the tail-gate, the platform-ramp being movable relative to the tail-gate from a loading position to an unloading position, and means carried by said tail-gate and operable upon raising of the gate from a horizontal ground level position to a horizontal position wherein the tail-gate is flush with the floor of the truck body to cause said platform-ramp to be elevated from its lowermost position to a position flush with the surface of the tail-gate.

2. A power-operated tail-gate for a vehicle body, comprising a U-shaped main portion having a bridge and flat arms extending rearwardly therefrom, said arms constituting load supporting sections spaced transversely from each other and defining an open central section, a plat-` form-ramp disposed in said open section, means operatively connectedto said tail-gate for raising said platform-ramp from a lovvermost position to an elevated position, and means operatively connected to said tail-gate which operates in response to movement of the tail-gate from a horizontal ground position to an elevated horizontal position to bring about raising of said platfrom-ramp to a position wherein n said platform-ramp is ush with the top surface of said tail-gate.

3. A power-operated tail-gate for a vehicle body, comprising an open section, a platformramp disposed in said open section, means connected to said tail-gate which operates in respouse to movement of the tail-gate from a horizontal ground position to an elevated horizontal position to bring about raising of said platform-ramp from its lowermost position to a position wherein said platform-ramp is ush with the top surface of said tail-gate, means for locking said platform-ramp in its elevated position, and means comprising lost motion mechanism for permitting the lowering of said tailgate frorn its elevated horizontal position to its lowermost position without movement of said platform-ramp relative to said tail-gate.

4. The combination as set forth in claim l, wherein said tail-gate and platform-ramp are operatively interconnected by a torque tube, a i

crank arm and a rotatable shaft, said platformramp being supported for movement on a rod pivotally connected to a pair of crank arms, and said crank arms being operatively connected to said shaft whereby rotation of said shaft causes i said platform-ramp to be swung angularly about said shaft.

5. The combination as set forth in claim 1J wherein said platform-ramp is locked in its elevated position by gravity operated latch means.

6. A power-operated tail-gate for a vehicle body comprising a plate for supporting loads, a rst shaft and a second shaft concentrically arranged and carried for rotation independently, at least one lifting arm having one end secured to said first shaft and the other end pivotally attached to said loading plate, means interconnecting the second shaft and said plate and adapted to translate the rotational movement of said second shaft to rotational movement of said plate about its axis of pivot with the lifting arm, means carried by the vehicle body and having a connection with said first shaft adapted to rotate said shaft to raise said lifting arm, means comprising a platform-ramp carried by said tailgate, and means operatively connected to said first shaft for bringing about the movement of said platform-ramp relative to said tail-gate upon the elevation of said tail-gate from its lowermost position.

'7. In a power-operated tail-gate for a vehicle body having associated therewith a central section comprising a platform-ramp, said platformramp being supported for movement relative to said tail-gate, and means carried by said tailgate for locking said platform-ramp against movement relative to said tail-gate.

8. A platform-ramp comprising a frame, a shaft supported for rotation in said frame, crank arms fixed to the opposite end portions of said shaft, a rod extending transversely of said frame and connecting the outer ends of said crank arms on which said platform-ramp is supported, rod means carried by crank arms spaced longitudinally of said platform-ramp for providing additional support for said platform-ramp, and means comprising links operatively connecting said crank arms whereby rotation of said shaft causes the simultaneous movement of said rods and platform-ramp supported thereon.

9. A power-operated tail-gate for a vehicle body having associated therewith a central section comprising a platform ramp to assist in loading and unloading the tail-gate, a first shaft and a second shaft concentrically arranged and carried for independent rotation, a pair of lifting arms having one end secured to the first shaft and the other end pivotally attached to the tailgate, means interconnecting the second shaft and the tail-gate and adapted to translate the rotation of the second shaft to rotation of the tail-gate about its axis of pivot with the lifting arms, power means carried by the vehicle body and operatively connected with the first shaft to rotate the rst shaft to raise and lower the lifting arms, crank arms pivotally connected to the tail-gate and to the platform-ramp and operatively connected to the lift arms to move the platform-ramp from ground-engaging positions to a position fiush with the tail-gate during the raising of the tail-gate to the level of the vehicle body, and a latch member carried by the tailgate and engaging the crank arms to lock the platform-ramp in the flush position with the tail-gate.

'teferenees Cited in the le of this patent UNITED STATES PATENTS 

